JPS60251688A - Semiconductor laser device - Google Patents

Abstract

PURPOSE:To obtain a semiconductor laser device, which oscillates at a single mode and operates at a low threshold, by forming multilayer thin-films containing double hetero-structure onto a substrate with a projecting section and shaping a region having a conduction type reverse to the uppermost layer of the multilayer thin-films to one part of the uppermost layer. CONSTITUTION:A forward mesa-shaped projecting section is formed onto an N type GaAs substrate 10 to a striped shape through photolithography. An N type Ga1-xAlxAs clad layer 11, a Ga1-yAlyAs active layer 12, a P type Ga1-x AlxAs clad layer 13 and an N type GaAs current limiting layer 14 are formed through a liquid-phase epitaxial method so that the film thickness of each layer is made thinner than other sections at the center of the projecting section. Zn is diffused to the surface of the uppermost layer of multilayer thin-films without a mask. Since a crystal growth layer at the center of the projecting section is made thinner than others at that time, a front 15 in a Zn diffusion region can be intruded only to the upper section of the projecting section of the P type Ga1-xAlxAs clad layer 13 by properly selecting the conditions of Zn diffusion. Accordingly, all of the Zn diffusion region display a P type.

Description

【発明の詳細な説明】 （産業上の利用分野） 本発明は、近年、民生用及び産業用の各種電子機器・電
気機器用光源として、用途が急速に拡大している半導体
レーザ装置に関するものである。DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a semiconductor laser device whose use has been rapidly expanding in recent years as a light source for various electronic and electrical devices for both consumer and industrial use. be.

（従来例の構成とその問題点） 電子機器、光学機器のコヒーレント光源として半導体レ
ーザに要求される重要な性能の１つに、単一スポットで
の発振、すなわち、単−横モード発振があげられる。こ
れを実現するためには、活性領域付近で、半導体レーザ
素子中を流れる電流の拡がりを抑制し、かつ、光を閉じ
込める必要がある。一般にこのような半導体レーザはス
トライプ型半導体レーザと呼ばれている。(Conventional configuration and its problems) One of the important performances required of a semiconductor laser as a coherent light source for electronic and optical equipment is oscillation in a single spot, that is, single-transverse mode oscillation. . To achieve this, it is necessary to suppress the spread of the current flowing through the semiconductor laser device and to confine light near the active region. Generally, such a semiconductor laser is called a stripe type semiconductor laser.

比較的簡単なストライプ化の方法としては、電流狭さく
だけによる方法がある。A relatively simple method for forming stripes is to use only current narrowing.

具体的には、プレーナ型半導体レーザにプロトン照射を
施したもの、Ｚｎ拡散を施したもの、酸化膜などの絶縁
膜を形成したものが挙げられる。これらの方法にはそれ
ぞれ欠点がある。プロトン照射を施すと、照射時に、半
導体レーザの各層の一部の結晶が損傷を受け、半導体レ
ーザの特性を損うことがある。Ｚｎ拡散型の場合、７０
０〜８５０℃というような高温で処理を行なうことが多
く、Ｚｎ等のドーパントの結晶中での移動が起こり、ス
トライプ化は可能であるが、狭ストライプ化は比較的離
しい。酸化膜などの絶縁膜による方法は、前記二つの方
法と比べて作製された半導体レーザ中での電流狭さくの
効果が弱いという欠点がある。Specifically, examples include those in which a planar semiconductor laser is subjected to proton irradiation, one in which Zn is diffused, and one in which an insulating film such as an oxide film is formed. Each of these methods has drawbacks. When proton irradiation is applied, some crystals in each layer of the semiconductor laser are damaged during the irradiation, which may impair the characteristics of the semiconductor laser. In the case of Zn diffusion type, 70
Processing is often carried out at a high temperature of 0 to 850° C., and dopants such as Zn move in the crystal, making it possible to form stripes, but forming narrow stripes is relatively difficult. The method using an insulating film such as an oxide film has a disadvantage in that the effect of narrowing the current in the manufactured semiconductor laser is weaker than the above two methods.

（発明の目的） 本発明は、上記欠点に鑑み、強い電流狭さくを行なうこ
とのできるストライプ構造の半導体レーザ装置を提供す
るものである。(Object of the Invention) In view of the above-mentioned drawbacks, the present invention provides a semiconductor laser device with a striped structure that can perform strong current constriction.

（発明の構成） この目的を達成するために、本発明の半導体レーザ装置
は、凸部を有する基板上に、二重へテロ構造を含む多層
薄膜を、その膜厚が凸部の上では他に比較して薄くなる
ように形成し、多層薄膜の最上層の一部に、その最上層
とは逆の導電型を有する領域を持つように構成される。(Structure of the Invention) In order to achieve this object, the semiconductor laser device of the present invention includes a multilayer thin film including a double heterostructure on a substrate having a convex portion, and the film thickness is different from that on the convex portion. The multilayer thin film is formed so that it is thinner than that of the multilayer thin film, and a part of the uppermost layer of the multilayer thin film has a region having a conductivity type opposite to that of the uppermost layer.

この構成により、強い電流狭さく用ストライプ構造が得
られ、単−横モード発振、低しきい値動作の半導体レー
ザ装置が容易に実現できる。With this configuration, a striped structure for strong current confinement can be obtained, and a semiconductor laser device with single-transverse mode oscillation and low threshold operation can be easily realized.

（実施例の説明） 以下、本発明の一実施例を、図面を用いて具体的に説明
する。(Description of Embodiment) Hereinafter, one embodiment of the present invention will be specifically described using the drawings.

一例として、基板はｎ型ＧａＡｓを用いる。第１図に示
すように、ｎ型ＧａＡｓ基板１０上にフォトリソグラフ
ィにより、順メサ状の凸部をストライプ状に設ける。次
にＬＰＥ法（液相エピタキシャル法）により、第３図に
示したように、ｎ型Ｇａ１−ＸＡｌｘＡｓクラッド層１
１、Ｇａ１−、ＡＮ、Ａｓ活性層１２（０≦ｙ＜ｘ）、
Ｐ型Ｇａ１−ｘＡ［ＸＡｓクラッド層１３、ｎ型ＧａＡ
ｓ電流制限層１４を、各層の膜厚が凸部中央では他の部
分に比べて薄くなるように形成する。なお、この時の結
晶成長条件は、基板温度が８５０℃、過飽和度７℃、ク
ーリングレート０．５℃／分で、通常のスライドボート
方式を用いた。この後、第３図に示すように、多層薄膜
最上Ｍ（電流制限層１４）の表面にマスクレスでＺｎ拡
散を行なう。この時、凸部中央の結晶成長層は他より薄
いので、Ｚｎ”拡散条件を適当に選ぶことにより、Ｚｎ
拡散領域のフロント１５をｐ型Ｇａ１−ＸＡｌｘＡｓク
ラッド層１３の凸部上部のみに入れることができる。こ
の結果、Ｚｎ拡散領域は全てｐ型を示す。ｎ−ＧａＡｓ
基板１０の底面１６と、ＬＰＥ成長層表面１７の両面に
電極を付け、電流を流したところ、電流が、第３図のス
トライプ幅Ｗで十分狭さくされ、６０ｍＡ程度のしきい
値で単−横モード発振する半導体レーザ装置が得られた
。また、第２図に示すように基板凸部を逆メサ形状にし
ても同様の結果が得られた。As an example, n-type GaAs is used as the substrate. As shown in FIG. 1, mesa-shaped protrusions are provided in stripes on an n-type GaAs substrate 10 by photolithography. Next, by the LPE method (liquid phase epitaxial method), as shown in FIG.
1, Ga1-, AN, As active layer 12 (0≦y<x),
P-type Ga1-xA [XAs cladding layer 13, n-type GaA
The s-current limiting layer 14 is formed so that the film thickness of each layer is thinner at the center of the convex portion than at other portions. The crystal growth conditions at this time were a substrate temperature of 850° C., a supersaturation degree of 7° C., a cooling rate of 0.5° C./min, and a normal slide boat method was used. Thereafter, as shown in FIG. 3, Zn is diffused onto the surface of the uppermost multilayer thin film M (current limiting layer 14) without a mask. At this time, since the crystal growth layer at the center of the convex part is thinner than the others, by appropriately selecting the Zn'' diffusion conditions, the Zn
The front 15 of the diffusion region can be placed only above the convex portion of the p-type Ga1-XAlxAs cladding layer 13. As a result, all the Zn diffusion regions exhibit p-type. n-GaAs
When electrodes were attached to both the bottom surface 16 of the substrate 10 and the surface 17 of the LPE growth layer, and a current was applied, the current was sufficiently narrowed by the stripe width W shown in FIG. A semiconductor laser device with mode oscillation was obtained. Further, similar results were obtained even when the convex portion of the substrate was formed into an inverted mesa shape as shown in FIG.

なお、本実施例では、ＧａＡｓ系、Ｇａ１Ａｓ系半導体
レーザについて述べたが、ＩｎＩ’系や他の多元混晶系
を含む化合物半導体を材料とする半導体レーザ装置につ
いても、本発明を適用することは可能である。In this embodiment, GaAs-based and Ga1As-based semiconductor lasers have been described, but the present invention can also be applied to semiconductor laser devices made of compound semiconductors including InI'-based and other multi-component mixed crystal systems. It is possible.

（発明の効果） 以上のように、本発明は、凸部を有する基板の上に、二
重へテロ構造を含む多層薄膜を形成し、その多層薄膜の
最上層の一部に最上層とは逆導電型の領域を形成するこ
とにより、強い電流狭さくを行なうことができ、従って
単一モード発振、低しきい値動作の半導体レーザ装置を
得ることができるものである。(Effects of the Invention) As described above, the present invention forms a multilayer thin film including a double heterostructure on a substrate having a convex portion, and forms a part of the top layer of the multilayer thin film with a By forming regions of opposite conductivity type, strong current confinement can be achieved, and therefore a semiconductor laser device with single mode oscillation and low threshold operation can be obtained.

【図面の簡単な説明】[Brief explanation of the drawing]

第１図は、本発明の一実施例で用いた順メサ形状の凸部
を有するＧａＡｓ基板の断面図、第２図は、他の実施例
の逆メサ形状の凸部を有するＧａＡｓ基板の断面図、第
３図は、本発明の一実施例の半導体レーザ装置の断面図
である。 １０−　ｎ型ＧａＡｓ基板、　１１−　ｎ型ＧａＡρＡ
ｓクラッド層、１２・・・ＧａＡＮＡｓ活性層、１３・
・・　Ｐ型ＧａＡ１！Ａｓクラッド層、　１４　＝・ｎ
型ＧａＡｓ電流制限層、　１５・・・Ｚｎ拡散領域のフ
ロント、　Ｗ・・・ストライプ幅。 特許出願人　松下電器産業株式会社FIG. 1 is a cross-sectional view of a GaAs substrate having a forward mesa-shaped convex portion used in one embodiment of the present invention, and FIG. 2 is a cross-sectional view of a GaAs substrate having an inverted mesa-shaped convex portion according to another embodiment. 3 are sectional views of a semiconductor laser device according to an embodiment of the present invention. 10- n-type GaAs substrate, 11- n-type GaAρA
s cladding layer, 12...GaANAs active layer, 13.
... P-type GaA1! As cladding layer, 14=・n
type GaAs current limiting layer, 15...front of Zn diffusion region, W...stripe width. Patent applicant Matsushita Electric Industrial Co., Ltd.

Claims (1)

【特許請求の範囲】[Claims] 凸部を有する基板上に、二重へテロ構造を含む多層薄膜
を、その薄膜が前記凸部の上では他の部分に比較して薄
くなるように形成し、前記多層薄膜の最上層の一部に、
その最上層とは逆の導電型を有する領域を設けてなるこ
とを特徴とする半導体レーザ装置。A multilayer thin film including a double heterostructure is formed on a substrate having a convex portion so that the thin film is thinner on the convex portion than on other parts, and one of the uppermost layers of the multilayer thin film is formed on the substrate having a convex portion. In the department,
A semiconductor laser device comprising a region having a conductivity type opposite to that of the uppermost layer.